This invention relates to the art of electronic cardiac pacemakers, and more particularly to a new and improved electronic cardiac pacemaker of the implanted type.
Early in the development of electronic cardiac pacemakers, the pacemaker electrodes were in the form of spiral platinum-iridium metal spring coils which were inserted surgically into the patient's myocardium after exposing his heart in a full thoracotomy under general anaesthesia. This was a great surgical shock to patients, especially those in aged and sick condition, and resulted in an early mortality rate of around 10 percent. Subsequent development by Dr. William M. Chardack of the implantable, transvenous, endocardial bipolar catheter essentially eliminated the high early mortality, and at the present time some 90 percent of all pacemaker surgical procedures are performed this way.
A recent development in pacemaker surgical procedures involves a limited thoracotomy whereby a helical type electrode is placed on one end of a long plastic rod and inserted into the patient through a small incision. The rod is rotated to install or screw the electrode into the patient's myocardium whereupon the rod is removed from the installed electrode and withdrawn from the patient.
It would, therefore, be highly desirable to provide an electronic cardiac pacemaker of the implantable type which is extremely small and provided with an integral electrode whereby the entire pacemaker is installed in a patient simply by rotating or screwing the pacemaker and integral electrode into the patient's myocardium in conjunction with a limited thoracotomy.